Prosthetic tibial components for replacement knee joints typically comprise a tibial tray which is coupled to the tibia of a patient and forms a tibial plateau of the tibia. The tibial component may be a unicondylar tibial component of a partial knee replacement prosthesis which replaces the proximal surface of a medial or a lateral tibial condyle. Alternatively, the tibial component may be part of a total knee replacement prosthesis and may replace substantially the complete proximal surface of the tibia and form a tibial plateau of the medial and lateral tibial condyles.
Often, separate bearing components are coupled to the tibial tray, which may be fixed bearing components or mobile bearing components. Fixed bearing components may additionally comprise mobile portions which are trapped within the fixed bearing. Any fixed bearing components must be coupled to the tibial tray to prevent movement and brackets are often provided on the posterior regions of the tibial tray which couple to the bearing components. The bearing components may comprise a pocketed recess in the posterior region of the bearing to couple with the bracket. The posterior portion of the bearing may be heavily loaded during some knee articulations and if a pocket is provided in this location, reinforcement may be required. In some cases it may be undesirable to provide a pocket in the posterior region of the bearing, for example to improve the rigidity of the posterior portion of the bearing.
During an operation to implant a prosthetic tibial component, which comprises one or more fixed bearing components, the surgeon may select from several bearing components of different thicknesses and may trial fit a bearing component of one thickness before selecting another thickness of bearing component to finally implant. For example, the surgeon may determine that the first bearing selected was too thick and was applying undesirable load into the prosthetic knee joint. The surgeon may trial fit several bearing components before selecting a bearing component with the correct thickness. It is therefore desirable to allow coupling and decoupling of fixed bearing components to be as simple as possible during surgery.